Mk248 mod 1

Why not shoot Mk248 Mod 1 spec ammo? The recipe is pretty broadly known.

https://usarmorment.com/pdf/300WM_load data.pdf

official recipe said:
3.4 Components. MK 248 MOD 1 cartridge components are the projectile, the cartridge case, the propellant, and the primer. 3.4.1 Projectile. The projectile for the MK 248 MOD 1 shall be DS/JXNN/C08/1604A5the 220 grain Sierra MatchKing® Hollow Point Boat Tail (HPBT) bullet, commercial part number 2240, manufactured by Sierra Bullets, (Drawing 53711-8330251). The bullet shall have a lead or lead alloy core and copper or copper alloy jacket. The bullet shall have a nominal weight of 220 grains, with a tolerance of ±0.5 grains. The bullet diameter shall be 0.3086-0.0005 inches. The bullet shall be of the reverse drawn, Open Tip Match (OTM) type capable of meeting the accuracy requirements as specified in paragraph 3.6.4. 3.4.2 Cartridge case. The cartridge case shall be .300 Winchester Magnum constructed of copper alloy in accordance with ASTM B19, and shall not be plated. The cartridge case shall meet the external dimensional requirements of ANSI/SAAMI Z299.4-1992. (C1) [A vent hole shall be present in the primer pocket of the cartridge case]. 3.4.2.1 Headstamp. The cartridge case headstamp marking shall consist of the identification code of the manufacturer, last 2 digits of year of manufacture and the notation "300 WM" or "300 WIN MAG" in accordance with drawing 53711-8330252. 3.4.3 Primer. The primer shall be a large match rifle primer, non-corrosive, nickel-plated, boxer type, and shall be of lead-styphnate type. The primer shall have a brass anvil and brass cup. The primer shall be capable of meeting the ballistic requirements herein. 3.4.4 Propellant. (C2) [Each cartridge shall contain Hodgdon H1000 propellant.] The propellant loaded in this cartridge shall contain flash reduction additives or coatings, and shall meet the temperature stability and ballistic requirements detailed in Section 3.6. 3.5 Complete cartridge. 3.5.1 Cartridge assembly. The cartridge assembly shall be manufactured and inspected in accordance with drawing 53711-8330252. 3.5.2 Primer seating depth. The primer shall be seated in the cartridge case to a depth of (M101) [0.000 to 0.008 inch below the face of the cartridge case head.] The primer shall not be staked or crimped in place. 3.5.3 Cartridge overall length. (M102) [The nominal overall length of the assembled cartridge shall be 3.500 inches maximum, 3.450 inches minimum] in accordance with drawing 53711-8330252. The distance from the cartridge case head to the 0.300 inch diameter datum on the projectile ogive shall be controlled to within ± 0.010 inches. The nominal overall length and the distance DS/JXNN/C08/1604A6from the cartridge case head to the 0.300 inch diameter datum on the projectile ogive of the assembled cartridge shall be established, within the above limits, by the manufacturer to meet performance requirements. 3.5.4 Cartridge headspace. (M103) [The cartridge headspace shall be 0.212 inches minimum, 0.220 inches maximum], in accordance with drawing 53711-8330252. Cartridge headspace shall be measured from the base of the cartridge case to the opposite surface of the belt of the cartridge case.
Click to expand...
 
how do you have a "mk248 mod1 " rifle?
you got your rem action tested for continued use of 68kpsi ammo ?
the rifle is a mk 13 mod something and the ammo is mk248 mod 1.
i am not sure i would do that.
working pressure of mk248mod1 is 68,100 psi
the oal length with the smk 220 is 3.5"
i built a loose clone mk13 rifle
i worked up a mk248 mod 1 load for my rifle and did well.
as i was not limited to USA powders, i tried rl26 and berger 230's
i am at 2912 fps with consistent hits at 1800 yds.
 
ar10ar15man said:
how do you have a "mk248 mod1 " rifle?
you got your rem action tested for continued use of 68kpsi ammo ?
the rifle is a mk 13 mod something and the ammo is mk248 mod 1.
i am not sure i would do that.
working pressure of mk248mod1 is 68,100 psi
the oal length with the smk 220 is 3.5"
i built a loose clone mk13 rifle
i worked up a mk248 mod 1 load for my rifle and did well.
as i was not limited to USA powders, i tried rl26 and berger 230's
i am at 2912 fps with consistent hits at 1800 yds.
Click to expand...
my rifle is a Remington 700 cloned to spec by Chad Dixon at Longrifles Inc with a mk248mod1 chamber. so far ive managed to find a pretty good group with the 215 berger hybrid with 77.9 g h1000. 3 shot group @ .176 with no pressure signs. just wondered how far I can go since im already way above published max
 
ar10ar15man said:
how do you have a "mk248 mod1 " rifle?
you got your rem action tested for continued use of 68kpsi ammo ?
the rifle is a mk 13 mod something and the ammo is mk248 mod 1.
i am not sure i would do that.
working pressure of mk248mod1 is 68,100 psi
the oal length with the smk 220 is 3.5"
i built a loose clone mk13 rifle
i worked up a mk248 mod 1 load for my rifle and did well.
as i was not limited to USA powders, i tried rl26 and berger 230's
i am at 2912 fps with consistent hits at 1800 yds.
Click to expand...
how much rl26 was behind the 230g berger?
 
So you had a rifle built with a custom chamber and aren't using the ammo that it's custom built for? What are you actually asking for then? Load data for unsafe .300wm loads?

I feel like I have to mention as well that since no two rifles are ever truly identical that it's 100% irrelevant what actual gun someone else is reloading for. Since this isn't some special case with high and low pressure load data like 6.5x55 or .45LongColt. Outside that specific kind of thing, it's the chamber that matters, not the brand/model. You will be best served at this point by stuffing this thread in the can and starting one with a title like "Looking for Berger 215gr Hybrid data for 300WM".
 
BallisticsGuy said:
So you had a rifle built with a custom chamber and aren't using the ammo that it's custom built for? What are you actually asking for then? Load data for unsafe .300wm loads?

I feel like I have to mention as well that since no two rifles are ever truly identical that it's 100% irrelevant what actual gun someone else is reloading for. Since this isn't some special case with high and low pressure load data like 6.5x55 or .45LongColt. Outside that specific kind of thing, it's the chamber that matters, not the brand/model. You will be best served at this point by stuffing this thread in the can and starting one with a title like "Looking for Berger 215gr Hybrid data for 300WM".
Click to expand...
I told him I wanted to shoot heavy bullets and when I opened up the package the barrel said mk248mod1 on the barrel. cant find that ammo anywhere. the 215 is what I could find locally but the 215 berger is not in bergers loading manual.
 
actually i would say you are wrong.
it is the THROAT and the HIGHER operating pressure in this case


cartridge is 3.5 with a smk220 it will chamber in a lot of std chambers.
the issue i see is he is using a bullet with a different profile, and the throat is cut for the 220 at 3.5

BallisticsGuy said:
So you had a rifle built with a custom chamber and aren't using the ammo that it's custom built for? What are you actually asking for then? Load data for unsafe .300wm loads?

I feel like I have to mention as well that since no two rifles are ever truly identical that it's 100% irrelevant what actual gun someone else is reloading for. Since this isn't some special case with high and low pressure load data like 6.5x55 or .45LongColt. Outside that specific kind of thing, it's the chamber that matters, not the brand/model. You will be best served at this point by stuffing this thread in the can and starting one with a title like "Looking for Berger 215gr Hybrid data for 300WM".
Click to expand...
 
you are over max for a 220 smk.
who knows where you are with a 215 berger.

bigal1964 said:
my rifle is a Remington 700 cloned to spec by Chad Dixon at Longrifles Inc with a mk248mod1 chamber. so far ive managed to find a pretty good group with the 215 berger hybrid with 77.9 g h1000. 3 shot group @ .176 with no pressure signs. just wondered how far I can go since im already way above published max
Click to expand...
 
ain't saying because i have a stiller action and you do not.
the navy SEAL's went to the stiller action BEFORE they went to the mk248mod1.
the 220 smk is right at the lands at the spec'd 3.5" length.

what bbl and bbl length do you have ?
bigal1964 said:
how much rl26 was behind the 230g berger?
Click to expand...
 
i will point out that i would run from a so-called gunsmith that wrote "mk248mod1" on a bbl and installed it in a rem 700 action. i seriously doubt that a 700 is designed TO BE SHOT A 10% OVER MAX ALL DAY LONG.

THERE IS A SPECIFIC BBL PROFILE FOR A MK 13...its called mk13
 
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